1. Field of the Invention
The present invention relates to component mounting apparatuses, and particularly to a subrack and corresponding plug-in units having code pins with simplified configurations for conveniently mounting the plug-in units into the subrack.
2. Description of the Related Art
Subracks for receiving plug-in units therein have been known in the electronics industry for a long time. A typical subrack comprises two sidewalls each having four corners, and four module rails fixed between the sidewalls, the module rails conventionally being screwed to the corresponding corners of the sidewalls. Bottom, top and back walls are attached to the subrack, and cooperate with the sidewalls to define a receiving space therebetween and an open side. The plug-in units can be inserted into and removed from the receiving space via the open side. The plug-in units typically comprise mounting panels engaging with two front module rails to thereby hold the plug-in units in place. For a thorough understanding of this kind of subrack, refer to the IEEE (International Electrical and Electronics Engineers) Standard 1101.10 established in 1996.
Various coding devices are used in subracks to enable plug-in units be correctly mounted to corresponding slide channels. Typically, combinations of code pins are used in the plug-in units. U.S. Pat. No. 5,019,947 discloses a coding device for plug-in units in subracks. The coding device comprises a subrack, a circuit board 6, and plug connection connectors 5. The subrack employs a plurality of coding elements 3 and a plurality of guide rails 2. The coding elements 3 each define two slots 4 therein. The plug connection connectors 5 respectively form two webs 7, 8 corresponding to the slots 4 of the coding elements 3. The webs 7, 8 corresponding to the coding elements 3 ensure that coding occurs as soon as the individual coding elements 3 are engaged on the subrack. However, this configuration complicates the manufacturing process of the subrack. In addition, for production of these rather elaborate components, complicated tools are required, and manufacturing of the additional coding elements 3 is quite expensive.
Thus, a new subrack for plug-in units with code pins which overcomes the above-mentioned problems is desired.